Does your dual zone climate control over compensate for sunlight?

[GTICam]

Thanks again prise.

I signed up for erWin, but haven't used it yet..

I pulled the dash sunlight sensor out this arvo. Neat piece of technology it is too! I'm trying a foil mask inside the plastic cover to see what happens.

Will post the results.

For me, the most noticeable effect was when driving from an shaded (underground) carpark out into the sunshine - the aircon would blast cold air in response to the increase sunlight. Lets see what happens now...

Cheers,
Cam.

[prise]

Before paying your flat fee to use erwin, make sure you have the software installed is specified in Step 1 of the Step by Step instructions. Otherwise you won't be able to view the training material.

[thevwbug]

Thanks again prise.

I signed up for erWin, but haven't used it yet..

I pulled the dash sunlight sensor out this arvo. Neat piece of technology it is too! I'm trying a foil mask inside the plastic cover to see what happens.

Will post the results.

For me, the most noticeable effect was when driving from an shaded (underground) carpark out into the sunshine - the aircon would blast cold air in response to the increase sunlight. Lets see what happens now...

Cheers,
Cam.

cam poped the guy out too added a few layers of duct tape to top, lets see what happens.

thebug

[prise]

cam poped the guy out too added a few layers of duct tape to top, lets see what happens.

thebug

Window tint film will achieve a partial reduction in the measured sun loading at the wavelengths of light that the sun sensor is responding to. You probably want to reduce, not eliminate the air-con reaction to sun loading.

[Idle]

cam poped the guy out too added a few layers of duct tape to top, lets see what happens.

thebug

A better test would probably be a lens from a fairly light pair of sunglasses over the sensor.

[thevwbug]

A better test would probably be a lens from a fairly light pair of sunglasses over the sensor.

Light does not seem to be visible though the cover, these must be a infrared sensor.

If anything the duct tape could give me a stable cabin temperature.

[thevwbug]

Light does not seem to be visible though the cover, these must be a infrared sensor.

If anything the duct tape could give me a stable cabin temperature.

So far so good, with nice hot sunny day the AC seems stable and comfortable set on 22 degrees. No massive bursts of freezing air

[GTICam]

Nice sunny Sydney day today and I can report that with a piece of foil inside the sensor it is much better. The fan speed control is much slower in response to sudden temp and light changes. It was noticeably more pleasant driving my GTI today with the aircon controlling off the temp sensor in the centre console rather than responding to the dash sensor.

I think it could probably do with a slightly more responsive sunlight temp sensor when the outside temps are around the 30 degree mark. Will try putting a small hole in the centre of my foil patch to see how it goes.

Cam.

[GTICam]

Light does not seem to be visible though the cover, these must be a infrared sensor.

It is an infrared sensor (actually 2 of them) and the plastic cover is a dark clear red - as you would expect.

I tried folding the corners on my foil mask (which sits above the infrared sensors, inside the cover) so it's pretty much a regular hexagon in shape. It stops sunlight directly on the sensors, but allows light to spill around the sides. Some of the responsiveness of the aircon returned, but it isn't overcontrolling. Seems pretty good now.

Also, if you put foil inside the cover like I did, you need to insulate the terminal pins on the top of the sensor circuit board. You'll see what I mean if you pull the cover off the sensor assembly.

[prise]

The temperatures I logged from the climatronic system are plotted here. The cabin temperature is regulated fairly well, but you can see how significantly the vent temperatures vary - a good reason not to have them pointed at your face!

http://dl.dropbox.com/u/14542234/LOG...11-581-601.pdf

[Corey_R]

The temperatures I logged from the climatronic system are plotted here. The cabin temperature is regulated fairly well, but you can see how significantly the vent temperatures vary - a good reason not to have them pointed at your face!

I think that's what the crux of the issue is here. Whether you have the vents aimed AT you, or AROUND you. Aircon vents should really be aimed AROUND you, and VW have clearly engineered the system to be configured as such. I personally only ever put the vents directly on me if I've just jumped into the car on a hot day when it was sitting in the sun, and then move them back so they are blowing air around me once cabin temps has returned to "normal".

[pologti18t]

I think that's what the crux of the issue is here. Whether you have the vents aimed AT you, or AROUND you. Aircon vents should really be aimed AROUND you, and VW have clearly engineered the system to be configured as such. I personally only ever put the vents directly on me if I've just jumped into the car on a hot day when it was sitting in the sun, and then move them back so they are blowing air around me once cabin temps has returned to "normal".

Seems to me VW have designed the system to predict potential temperature changes and nip them in the bud before cabin temps deviate too much to what you set.

[GTICam]

That's an impressive plot "prise". Thanks for posting it. Shame it doesn't show fan speed too. Amazing how you can see the massive hyseresis in the aircon system control. No wonder, with the short coupling of the sunlight sensor on the dash to the fan speed, it overcompensates when driving into direct sunlight.

The mask I'm using inside the dash sunlight sensor cap seems to be keeping the fan speed under better control, and the cabin temps much more even.

BTW. Corey R, I tried the vents in all positions (I mostly drive with the airflow directed into the cabin, not blowing over me) and even tried the various manual vent selection positions to no avail. The Golf system works, but is just too clever for it's own good. Same deal in my book for the auto wipers. Overengineered high tech crap.

[logger]

..also be interesting to compare sensed cabin temp to true cabin temp as felt by the occupant. Good chance they differ somewhat depending on where the systems sensor is located.

[prise]

The cabin temperature sensor is located behind the dimple in the glossy black panel just below the top row of buttons on the HVAC control panel. It appears to be sensitive to a combination of the surface temperature of the materials inside the cabin (eg, an IR thermometer) and the air temperature. In this respect it is different to the previous generaton systems that measured air temperature only. That is probably why it is returning a higher reading than the set temperature (the air temp certainly didn't 'feel' like 25 deg).

I'll log fan speed and AC compressor load next time round and I think I've still got a reasonably accurate old style 'bulb' thermometer lying around to compare with the cabin air temp.